1 million points is a large dataset but ArcMap should be able to handle that. In my experience large datasets often have errors in them. Have you run your point dataset through the check geometry tool, may be you have null geometries? Do all fields have values, e.g. no null value?

1 million points is a large dataset but ArcMap should be able to handle that. In my experience large datasets often have errors in them. Have you run your point dataset through the check geometry tool, may be you have null geometries? Do all fields have values, e.g. no null value?

Duncan

Thank you Duncan. I have used the check geometry tool, everything was ok. But then I used the delete identical tool. After this tool, the thiessen polygon calculation worked.